The present invention relates generally to the application of protective coatings on uranium and, more particularly, to a method of applying an impervious protective coating of copper on uranium.
Bare uranium metal is readily corroded by contact with various atmospheric gases and aqueous solutions. In order to utilize uranium metal in most applications it is necessary to provide the uranium article with a protective coating which will inhibit or minimize the deleterious corrosion of the uranium. Also, the joining of the uranium metal to other components or of other metals to uranium metal by brazing, welding, and the like, frequently necessitates the use of a metal coating on the uranium which will facilitate the joining thereof.
Uranium metal has been subjected to various coating materials. Some previously used coating metals, e.g, tin, permit diffusion of the uranium through the coating so as to minimize the value of the coating. Under certain conditions other metals, such as nickel, provide a satisfactory coating but form a very brittle intermetallic with the uranium at temperatures greater than about 480.degree. C. (brazing temperatures) so as to form cracks and crevices therein and thereby to effectively reduce their usefulness as a satisfactory interface for various joining procedures and as a corrosion inhibiter. Copper has been found to provide a suitable protective coating and also to function as a satisfactory interface for various welding procedures. However, the application of copper coatings on uranium as previously practiced has not been satisfactory since blisters formed in the coating which not only weakened the coating but also permitted the corrosion of the underlying uranium to readily occur.